What do the following two equations represent? $5x+5y = -5$ $-15x+15y = -3$
Putting the first equation in $y = mx + b$ form gives: $5x+5y = -5$ $5y = -5x-5$ $y = -1x - 1$ Putting the second equation in $y = mx + b$ form gives: $-15x+15y = -3$ $15y = 15x-3$ $y = 1x - \dfrac{1}{5}$ The slopes are negative inverses of each other, so the lines are perpendicular.